August 25, 2009

AutoCAD 3D Conceptual Design 114

In a previous post I used the Union and Subtract tools to create a composite solid from primitive objects. Even though this process produced a single object, I can still edit the primitive sub-objects within the composite solid. The key is control… or I should say CTRL is the key! If you hold down the CTRL key as you pass the cursor over the composite solid, AutoCAD highlights each sub-object.

You can then click to select the highlighted sub-object. Once it’s selected, you can use grips or the Properties palette to edit the primitive properties in the same you that you could before performing the Union or Subtract operation. For example, if you want to shorten the handle on the air hockey paddle, you might select the stretch grip and move it down 15 units. Notice the edit only affects the cylinder. In AutoCAD there are no constraints between 3D shapes (unlike parametric 3D design applications such as Inventor and Revit).

As I mentioned, you can also edit sub-objects using the Properties palette. Notice that even though the cylinder is a sub-object in the composite solid, all the typical cylinder properties are available for editing. I’ll change the radius of the cylinder to 13 and the height to 34.